Satellites are vulnerable to the existing Soviet ASAT weapon, to the U.S. ASAT under development, to the large numbers of ICBMs in existence, and to many future threats, including space mines. An ban on ASAT use and test is adequately verifiable to increase U.S. security and to reduce the likelihood of at least one cause of war. The U.S. should move with urgency to negotiate such a ban with the Soviet Union and then with other nations, because the ability efficiently to destroy the satellites of others is less valuable to the U.S. than the reduced threat to our own satellites under a treaty regime.